1. Field of the Invention
The present invention relates to an optical disc drive, and more particularly, to an apparatus and related method for generating a tracking error signal in the optical disc drive.
2. Description of the Prior Art
A servo system in an optical disc drive needs to utilize a tracking error signal TE for dynamically controlling a laser diode of a pick-up head (PUH) to output a laser beam to an optical disc track. The conventional method utilizes an optical sensor on the PUH to sense a reflected beam from the optical disc to generate a plurality of analog signals, utilizes an ADC to convert the plurality of analog signals to a plurality of digital signals with a specific sampling rate, and then generates the tracking error signal for the servo system.
However, quality of the tracking error signal relates to the sampling rate of the ADC. If the ADC converts the plurality of analog signals to a plurality of digital signals with a fixed sampling rate, quality of the tracking error signal is not always the same when different tracks on the optical disc are read or the reading condition changes.
Additionally, the conventional method generates the tracking error signal according to four signals A, B, C, D detected from the optical sensor. For example, the tracking error signal can be generated by subtracting a phase difference between the signals A and B from a phase difference between the signals C and D.
However, the phase difference value between the signals A and B and the phase difference value between the signals C and D are not equally important in every situation. When one is more important than the other, the synthesis method with equal weighting factors for generating the tracking error signal is not the optimal method to represent the tracking error information.